Leaf discoloration

Hey y’all, I’ve got an issue with one of my plants. I’m thinking it has to do with Ca/mag/ iron or maybe ph.
Strain: Alaskan Thunderfuck

Medium: Transplanted a week ago from straight FFOF
into a mix of 50/50 FFOF/HF, 40% perlite, 1 big scoop of EWC and 1/2cup of mychorrizae. 5 gal fabric pots. Watered in with kelp extract.

Nutrients: watering with molasses (1 tsp/gal) and Humboldts Best “Killer tea” (2tsp/gal). Every other watering they get Roots Organics “Extreme Serene”. I have no problem backing off on these until mid flower if that’s the issue. That was kinda the point of the transplant but I want them BIG.

Lights: waiting on my alibaba meijiu 480w LED board. Currently running an HLG 100v2, a random blurple, and 4 cfls (86w total). Rotating the plants everyday as to share the light!

4’x4’x6.5’ tent with ac infinity t6 fan and carbon filter. Running low on temp (70-76 during the day) but humidity is fine.

I have a bluelab ph pen, but only a small amount of the KCl solution so I have yet to actually use it. I might calibrate it’s today though and just find a way to get some liquid in the cap..
Any help would be appreciated guys I’m having a hard time finding info about this problem on other sites.
Much love and happy growing.

The more I look the more I think it’s magnesium.
Would a foliar Epsom salt spray help?
Is it more about my ph? Please help guys

I’m thinking iron

Weouthere said:

The more I look the more I think it’s magnesium.
Would a foliar Epsom salt spray help?
Is it more about my ph? Please help guys

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It definitely resembles Mg deficiency, but since you don't know what your pH is of your water/feed is, that could definitely be the cause. Too high or low pH and nutrients can get locked out.

Get your pH meter put to use. Ensure pH of water going in is stable for a few feeds, then revisit possible deficiencies.

RedLeonard said:

I’m thinking iron

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Iron is an immobile nutrient, meaning that issues related to its deficiency show up in the new growth (top of the plant). OPs issue is in the lower leaves which typically indicates a mobile nutrient deficiency. Magnesium is a mobile nutrient.

The reason that mobile nutrient deficiencies start at the lower portions of the plant is because mobile nutrients are moved around the plant to where they are needed most.

Nitrogen is a great example here. When you start showing signs of N deficiency, it's at the bottom of the plant. That's because the plant isn't uptaking any more from the root system, so it literally moves the N from the oldest leaves, and uses it at the new growth.

Immobile nutrients stay where they are first allocated, and can not be moved around. Iron (Fe) being immobile, will show symptoms at the top of the plant because when the root system fails to uptake more, the plant can't shuffle Iron from elsewhere in the plant to feed the new growth.

Most of the nutes are immobile. If my memory serves correctly, N, K, P, Mg and Zc are the mobile nutrients and all others are immobile.

Knowing which nutrients are mobile and which aren't helps in "halving" the problem to a specific group of nutes. Once you know if it's a mobile or immobile nutrient deficiency, you've only got a subset of deficiencies to compare against.

spek9 said:

It definitely resembles Mg deficiency, but since you don't know what your pH is of your water/feed is, that could definitely be the cause. Too high or low pH and nutrients can get locked out.

Get your pH meter put to use. Ensure pH of water going in is stable for a few feeds, then revisit possible deficiencies.

Click to expand...

So I’ve got my bluelab pen presoaking right now. I’ll be able to use it at about 10 tonight, honestly I’m really excited.
I’ll test my mix that I used (I still have like a half gallon) and my mix that I plan on using. Tomorrow when I water I’ll do a runoff test as well.
I did do like a PH slurry(?) test with soil/powder and water last night. My ph for my soil at least was about 6.8. Hard to tell with the color strips but it was for sure between 6.5 and 7.
I also sprayed the plant with Epsom salts (1tblsp/gal) in hopes of a good foliar feed. I do see some remnants on the leaves this morning though

Just got the bluelab pen calibrated and spent a good hour doing tests.
Pausing in the middle to smoke a couple bowls and post this lol!
So I tested my
straight tap water that I’ve been using for watering - ph 7-7.1
Tap water after adding compost tea (2tsp) - ph 7-7.1
Then I added GH ph down at a rate of like 12 drops per gallon. Got it down to 6.6.
Gonna go ahead and water now. I’ve noticed I haven’t been giving them nearly enough water either.. been giving about a 3/4 liter in 5 gal air pots. Going for 3/4 GALLON tonight. Should fix some of the issues hopefully!
In the future should I ph my water down even lower, say to 6.4ish?

Ended up giving them each a gallon of water! Tested each runoff separately. They ranged from ph 5.9-6.1. Four of the six plants were at ph 6.0.

I had the same look on my leaves i ran ph water for a bit and cut food back. Mine was to much nitrogen once i quit feeding and let it got a week with just ph water color on new growth looked correct

SgtPringles said:

I had the same look on my leaves i ran ph water for a bit and cut food back. Mine was to much nitrogen once i quit feeding and let it got a week with just ph water color on new growth looked correct

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Gonna do this the next few watering thanks man